Peralta, Nickole Q.2026-10-152026-10-152015-03Peralta, N.Q. (2015). Quality of groundwater in selected barangays of Luna and Sto. Tomas, La Union. [Unpublished Master's Thesis]. Don Mariano Marcos Memorial State University - South La Union Campus, Agoo, La Union. Lakasa ti Sirib, DMMMSU Institutional Repository.https://lakasa.dmmmsu.edu.ph/handle/123456789/2783Abstract OnlyAccess to safe drinking water which comes from groundwater is essential for a healthy life. In the barangays of Luna and Sto. Tomas, La Union household residents rely on the use of pump wells to obtain groundwater for drinking and domestic uses but its quality is in question. Using the standard laboratory methods, this study determined the bacteriological and physical quality of groundwater samples from 16 barangays of the two towns. Results showed that the water samples taken from the 16 shallow and deep wells which are constructed in loam and sand topsoil ~ contained varying levels of bacteria. The 14 water samples were contaminated with total coliforms, fecal coliforms and E. coli, thus, failed in the standard guidelines. Only two groundwater samples obtained from Oaqui 3 and Poblacion 2 (Baraca) were negative of the three groups of bacteria. Both passed the national and international standards for drinking water.enThesis